This invention relates to certain new chemical compounds. More particularly it relates to certain chemical compounds which have valuable medicinal properties, and which are new members of the class of compounds known as the prostaglandins.
The prostaglandins are derivatives of the C-20 fatty acid 7-(2.beta.-octylcyclopent-1.alpha.-yl)heptanoic acid, which is also known as prostanoic acid and is depicted as follows: ##STR1## Prostaglandins exist naturally and they have been isolated from a variety of mammalian sources. Natural prostaglandins of the so-called "E-series" have an oxo group at C-9, a hydroxy group at C-11 trans to the adjacent eight-carbon side chain at C-12, and an .alpha.-hydroxy group at C-15. Individual members of the E-series of prostaglandins can be further characterized by the number and location of double bonds in the C-8 and C-12 side chains. For example, prostaglandin E.sub.1 has a 13-14 trans double bond, and prostaglandin E.sub.2 has a 13-14 trans double bond and a 5-6 cis double bond. Prostaglandin E.sub.2 is also named as 9-oxo-11.alpha.,15.alpha.-dihydroxy-cis-5-trans-13-prosta-5,13-dienoic acid, and it has the following structure: ##STR2##
Prostaglandins of the E-series cause a wide variety of biological and pharmacological responses, both in vitro and in vivo. For example, E-series prostaglandins stimulate uterine smooth muscle, have hypotensive, diuretic, bronchodilatory and antilipolytic activities, and also have effects on blood platelet aggregation and gastric acid secretion. (See further: Bergstrom et al., Pharmacological Reviews, 20,1(1968) and Caton, progress in Medicinal Chemistry, Butterworths Publications, Ltd., London, 1971, Volume 8, page 317). However, in order to increase their medicinal usefulness, it is desirable to have compounds with a greater specificity of action. Accordingly it is an object of this invention to provide certain derivatives of prostaglandins E.sub.1 and E.sub.2 which have useful bronchodilatory properties, but which have substantially no effect on uterine smooth muscle and reduced hypotensive and gastric antisecretory effects.